The description should specify that it's looking for total surface area of the box.

I disagree, if you're asked to calculate the area of the box, it's implicit it's the total area, and not the area of the base, it's a 3D element after all, why would you only calculate the area of one side? Anyway, if adding total before area makes it clearer, go for it.

I see, I did not notice that description for SQL is so different from other languages.

I will try to improve the description.

The description should specify that it's looking for total surface area of the box. That's what it says in eg python, and it caused me (and evidently others) confusion for SQL that it just says area. (I, like someone else in the comments, thought that area meant the area of the base of the box)

Your solution calculates area of a box incorrectly.

Remember that a box has six sides, and total area of a box is a sum of areas of all six sides.